When we first reviewed the HD6990 we found it to be a phenomenally impressive card. A total powerhouse. However the main issue was, as it is with most of the current range of Radeon cards, heat and noise.

The perfect solution to any heat problem is to go from air-cooling to water-cooling. Modern CPU coolers are of such high-quality that water-cooling isn't such a desperately important thing for the heart of our machines, but graphics technology has continued apace and almost outstripped the capabilities of standard air-cooling to keep the cards cool. So water-cooling is ideal for our power-hungry, eye-candy providing behemoths.

Enter PowerColor with their take upon the HD6990 with a factory fitted EK Waterblock. A perfect opportunity to get a system built we think.

Technical Specifications

Aside from the addition of the EK Waterblock, the PowerColor HD6990 is a standard card beneath that Delrin exterior.

Graphics Engine

RADEON HD6990

Video Memory

4GB GDDR5

Engine Clock

830MHz / 880MHz

Memory Clock

1250MHz (5.0Gbps)

Memory Interface

2 X 256bit (256bit)

DirectX® Support

11

Bus Standard

PCIE 2.1

Standard Display Connecors

Dual-link DVI-I / 4 X mini DisplayPort

OpenGL

Support

CrossFireX™ Technology

Support

ATI Stream Technology

Support

ATI Eyefinity Technology

Support

ATI Hypermemory Technology

VGA Output

Yes, By DVI to VGA converter

DVI Output

Dual-link DVI-I / 4 X mini DisplayPort

DisplayPort

On Board

HDMI

On Board

TV Output

HDTV Output

HDCP Support

Support

VGA

2048x1536

DVI

2560x1600

DisplayPort

2560x1600

HDMI

1920x1200

Board Dimensions

305mmx110mmx38mm

Minimum System Power requirement (W)

750W

Extention Power Connector

two 8-pin PCI Express Power connectors

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Up Close

As by now we all know what a HD6990 looks like, and the none-more-black top of the LCS is fairly self-explanatory, let's have some nerd porn by showing you around the Shadow H20 which I'm sure the Youtube watchers have already seen.

Two 8pin PCIe power connectors keep the HD6990s twin GPUs working at full capacity.

Doesn't it all look fabulous stuffed into the Rampage III Black Edition and the HAF case. No matter how gorgeous some of the heat-pipe arrangements are these days, the minimalism of a water-loop always gets our hearts pumping a bit faster.

Naturally things like this don't just fall into place so we have to give some props to the many companies for lending us the bits to make this possible.

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Test Setup

As part of our Shadow H20 there are a few slightly different specifications to our normal test setup. However we are sure that the system is close enough to our normal one to maintain the validity of results comparison. The only change to be wary of between the PowerColor HD6990 LCS and the other results in our graphs is that they were done at 1920x1200 and this is 1920x1080, so they'll be a slight improvement as there is 230000 less pixels to render.

Without the heat problem restricting our overclocking efforts the PowerColor was capable of some serious extra oomph. The GPU falling just shy of 1GHz and the GDDR5 having an extra 150 MHz.

Temperatures

Proving how efficient a water-cooling setup is, especially for graphics cards, we saw a maximum temperature of only 50°C. This is an incredible improvement over the 80°C-ish that we get from the stock air-cooled card.

Let's get down to some benchmarks.

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3D Mark Vantage

The enormous overclock we're able to squeeze out of the PowerColor really helps push the LCS into new heights in 3D Mark Vantage. Of course a Radeon wont quite best an nVidia card in this particular benchmark, but 30000 in the High test is nothing to be sniffed at. The Extreme setting is missing as 3D Mark Vantage requires 1920x1200 for this but our Iiyama monitors are 16:9.

3D Mark 11

With the additional overclock our HD6990 finally breaks through the 10000 barrier in 3D Mark 11 and ends up second only to the awesome power of the GTX580 SLI setup.

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Unigine

0xAA

Demonstrating what we thought when we reviewed the HD6870X2 last week, the latest Catalyst drivers are hugely hampering the Unigine results compared to earlier revisions. Still 87 FPS is more than plenty considering the levels of detail Unigine provides.

8xAA

Even with 8x Anti-Aliasing the power of the HD6990 LCS cannot be contained.

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Alien vs Predator

When it comes to Giger inspired slaughter there is a new King on the block. The PowerColor is a full 8FPS ahead of the GTX580 SLI and 20 FPS ahead of the stock HD6990.

Call of Duty - Black Ops

If you're a fan of the Infinity Ward shooter then you have nothing to worry about here, or to be honest with any card. It's a surprise to see the LCS behind the stock HD6990 though. Albeit only a couple of frames.

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Crysis 2

Firstly it's worth pointing out that this is not in v1.9 DX11 mode, that's going to be an upcoming test, so for now these results are for the 'vanilla' version of Crysis 2. The PowerColor absolutely creams the stock card getting up to the 100 FPS average, although obviously it's not a patch on the GTX590.

Metro 2033

Always a fan of twin-GPUs, Metro 2033 definitely enjoys the benefits that the PowerColor HD6990 LCS brings to the table. The PowerColor is a whopping 15 frames on average ahead of an overclocked air-cooled HD6990. It's 30 frames behind the beast that is the GTX590, largely thanks to the heavy use of PhysX.

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Medal Of Honor

Similar to Black Ops, MoH really doesn't have the oomph to stress these cards thanks to their console roots. It's worth noting how much of a huge boost the overclock gives to the minimum frame-rate. A playing experience as smooth as butter.

PC Mark 7

Just in case any of you wondered what this kind of combination of high-end parts would give in general performance terms, here is the PC Mark 7 result for the system as a whole. Start saving those pennies.

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Conclusion

When we first reviewed the HD6990 back in March we found it to be an absolute powerhouse of a card. Amazing performance let down enormously by a truly woeful cooler that made a hell of a lot of noise but didn't really do the cooling part well.

Since then we've seen the GTX590 which was around the same power but with infinitely better cooling, and now we've got the PowerColor HD6990 LCS. All the power of the HD6990 but with none of the noise.

Of course the main benefit we've seen from the switch to liquid cooling, heat and noise aside, is the ability to really clock this card hard. It seems to find itself free from the shackles once you head towards the 1GHz mark and the benchmarks back this up.

In the tests that it was behind the GTX590 it's now much closer and, driver issues with Unigine notwithstanding, the tests that it had a lead in that lead is now healthy.

The inclusion of a factory fitted EK Waterblock is a good one. It would be tempting to fit some generic block to try and keep the profit margin up there, but by using the EK we have one of the premier water-blocks, with all the safety and worry-free ownership that a manufacturer fitted block and the subsequent retention of the warranty gives.

In fact the only setup that consistently beats the PowerColor is a GTX580 SLI one. Therein lies the main decision to be made. Because the HD6990 is already an expensive card the water-block fitting pushes the PowerColor into the price realms of a GTX580 setup. So if you've already got a water-loop and want a card, this is clearly the chappy. If you're just looking for the ultimate performance then it's tough to look past the GTX580 SLI.

Either way if you've got a mattress stuffed full of fifty pound notes and are wondering what to spend it on, the PowerColor HD6990 LCS is a mighty powerful card that fixes all of the problems of the reference design and an easy winner of the OC3D Gold Award.